This phase II, multicenter, randomized, double-blind, parallel-group, placebo-controlled study will evaluate the efficacy and safety of RO4602522 in patients with moderate severity Alzheimer disease. Patients who are taking background therapy of acetylcholinesterase inhibitors alone or in combination with memantine for at least 4 months before screening will be randomized to receive either one of two doses of RO4602522 or placebo for 12 months.

Probable Alzheimer disease, based on the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS)/Alzheimer's Disease and Related Disorders Association (ADRDA) and DSM-IV-TR criteria

Receiving treatment with donepezil or rivastigmine, galantamine or any of these AChEIs in combination with memantine for at least 4 months before screening, with their dose and formulation stabilized at least 3 months before screening. All formulation and dosages are allowed except donezepil 23 mg (alone or in combination)

Females of childbearing potential must have a negative pregnancy test and must agree to use effective contraception

Generally healthy and ambulatory or ambulatory-aided (i.e., walker or cane)

Have a reliable caregiver or some other identified responsible person who has frequent contact with the patient

Exclusion Criteria:

Any neurological or psychiatric condition that may currently or during the course of the study impair cognition or functioning that is not associated with Alzheimer's disease

Alcohol and/or substance abuse or dependence (DSM-IV-TR) in the past 2 years, except nicotine use which is allowed. However, smokers treated with nicotine replacement therapy or bupropion are excluded

Unstable or poorly controlled hypertension as assessed by the investigator

Unstable or clinically significant cardiovascular disease that could be expected to progress, recur, or change during study period to such an extent that it could bias the assessment of the clinical or mental status of the patient

Inadequate hepatic, renal or thyroid function

Positive for hepatitis B, hepatitis C or HIV infection

Poorly controlled diabetes

Requiring nursing home care. Patients living in assisted living facilities are allowed if a reliable caregiver is available (see inclusion criteria)

Current treatment for AD other than those listed in inclusion criteria

Participation at any time in an active AD vaccine study

Participation in a passive AD immunization study less than 1 year before screening, with exceptions as per protocol

Psychotropic medication as defined by protocol

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01677754